Adding salt water is endothermic and separating them is exothermic fwiw. That is separating salt from water releases energy. There's nothing perpetual motion a

Adding salt water is endothermic and separating them is exothermic fwiw. That is separating salt from water releases energy. There's nothing perpetual motion about a process that separates fresh water and salt and also gives energy. I'm not sure if the above works or not but physically there's no issue with this.